信号处理改善波长调制光谱灵敏度的实验研究

基于可调谐半导体激光吸收光谱，提出了一种新的信号处理方法用于提高吸收光谱测量的灵敏度. 研究结果表明：采用信号处理（DSP）可以使波长调制光谱的信噪比提高一个数量级,且测量CO₂分子的时候发现一条新谱线. 这些信号处理包括多次平均、数字低通滤波以及最小二乘法拟合. 由于该方法不需要增加设备的复杂性，所以比其他噪声抑制技术更容易在实验中实施、有更实际的应用价值.关键词：波长调制信号处理半导体激光器吸收光谱

Experimental research on the sensitivity of wavelength modulation by signal processing

We present a signal-processing system developed for enhancing the sensitivity of absorption measurement based on tunable diode laser wavelength modulation spectroscopy. A signal-to-noise ratio enhancement of an order of magnitude was observed when digital signal-processing algorithms were applied to wavelength modulation spectrometers in the near-infrared，at the same time a new spectra was found by observation of CO₂ near 1.53 μm. These algorithms include digital low-pass filters, multiple averages, and a least squares fit. Digital signal processing has a practical advantage over other noise suppression techniques because it is easy to implement and adapt able to all experiments.